This present invention relates generally to manufacturing objects. More particularly, the invention relates to a method and structure for fabricating a spatial light modulator with a high fill ratio. Merely by way of example, the invention has been applied to the formation of a spatial light modulator having an all silicon mirror, torsion spring hinge, and top electrode. The method and device can be applied to spatial light modulators as well as other devices, for example, micro-electromechanical sensors, detectors, and displays.
Spatial light modulators (SLMs) have numerous applications in the areas of optical information processing, projection displays, video and graphics monitors, televisions, and electrophotographic printing. Reflective SLMs are devices that modulate incident light in a spatial pattern to reflect an image corresponding to an electrical or optical input. The incident light may be modulated in phase, intensity, polarization, or deflection direction. A reflective SLM is typically comprised of an area or two-dimensional array of addressable picture elements (pixels) capable of reflecting incident light.
Some conventional SLMs utilize array designs that include an array of micro-mirrors with a set of electrodes and a memory array positioned underneath each of the micro-mirrors. For display applications, the micro-mirrors are generally fabricated using semiconductor processing techniques to provide devices with dimensions on the order of 15 μm×15 μm. Using such small mirrors enables display applications to use SLMs in applications characterized by increased image resolution for a given display size. Merely by way of example, HDTV systems, with a resolution of 1,080 scan lines×1,920 pixels/line, are currently available to consumers.
One option for increasing the number of micro-mirrors in an array is to add additional micro-mirrors to the array. However, the addition of micro-mirrors of a conventional size increases the silicon real estate used to fabricate the array. Another option is to add additional micro-mirrors while decreasing the size of the individual micro-mirrors, thereby maintaining a generally constant array dimension size. The use of current materials and fabrication processes presents design and manufacturing problems as the mirror size is decreased. Thus, there is a need in the art for a spatial light modulator with an improved architecture including materials and fabrication processes.